.middle > div {
    border: 1px solid red;
}

.middle > div > div:nth-child(2) > div:nth-child(1) > div {
    text-align: center;
}

.middle > div > div:nth-child(2) > div:nth-child(2) {
    display: flex;
    justify-content: center;
}

/*为了让表单居中*/
.middle > div > div:nth-child(2) > div:nth-child(2) > div {
    width: 800px;
    /*border: 1px solid red;*/
}

.middle > div > div:nth-child(2) > div:nth-child(2) > div > div > div:nth-child(2) {
    background-color: rgb(238, 238, 238);
    border: 1px dashed red;
    line-height: 50px;
    padding: 0 20px;
}

.middle > div > div:nth-child(2) > div:nth-child(2) > div > div:nth-child(3) > div:nth-child(2) {
    height: 200px;
    line-height: 20px;
    padding: 20px;
}

/*提交*/
.middle > div > div:nth-child(2) > div:nth-child(2) > div > div:last-child {

    display: flex;
    justify-content: center;

}

.middle > div > div:nth-child(2) > div:nth-child(2) > div > div:last-child > div {
    text-align: center;
    padding: 10px 30px;
    background-color: rgb(230, 145, 55);
    margin: 30px;
    cursor: pointer;
    box-shadow: 1px 1px 5px 5px  red;
}